Anti-single phasing device

ABSTRACT

A motor controlling system, including a conventional multipole electromagnetic contactor and associated overload relay means, is provided with motor short circuit protector means in the form of fast acting fused protector units connected in series with the heaters of the overload relay means and the motor windings. Under relatively low fault current conditions, the overload relay means opens the contactor actuating coil circuit, and under severe fault conditions the fused protector units become active to open the energizing circuit for the holding coil of the electromagnet. At currents in excess of 5.5 to 6.5 times full load motor current, this being the locked rotor current for most motors, the fused protector unit blows faster than the overload relay trips, thereby protecting the branch wire contactor and the overload relay means. Actuation of a fused protector unit causes an ejector pin thereof to operate a common trip bar which, in turn, opens a switch in the coil circuit. This trip bar is part of an anti-single phasing unit that is selectively positionable with respect to the clips which mount the fused protector units, thereby cooperating with fused protector units of different sizes. These clips are provided with integral formations which serve a blocking or non-interchangeability function, thereby preventing oversized fused protector units from being mounted to the clips. The antisingle phasing unit and protector unit holding clips are mounted on one surface of a relatively shallow molded housing having disconnect switch means mounted therein.

Krueger Feb. 12, 1974 ANTI-SINGLE PHASING DEVICE Keith Theophil Krueger,Bellefontaine, Ohio [75] Inventor:

[73] Assignee: ITE Imperial Corporation,

Philadelphia, Pa.

[22] Filed: May 8, 1972 [2]] Appl. No.: 251,288

[52] US. Cl 200/169 R, 337/7, 337/46, 337/50, 337/146 [51] Int. Cl. H01h3/20, HOlh 85/00 [58] Field of Search.. 317/46; 337/7, 8, 45, 46, 146,337/38, 50, 78; 200/16 A, 169 R Primary Examiner-Bernard A. GilheanyAssistant Examiner-A. T. Grimley Attorney, Agent, or FirmOstrolenk,Faber, Gerb & Soffen [57] ABSTRACT A motor controlling system, includinga conventional multipole electromagnetic contactor and associatedoverload relay means, is provided with motor short circuit protectormeans in the form of fast acting fused protector units connected inseries with the heaters of the overload relay means and the motorwindings. Under relatively low fault current conditions, the overloadrelay means opens the contactor actuating coil circuit, and under severefault conditions the fused protector units become active to open theenergizing circuit for the holding coil of the electromagnet- Atcurrents in excess of 5.5 to 6.5 times full load motor current, thisbeing the locked rotor current for most motors, the fused protector unitblows faster than the overload relay trips, thereby protecting thebranch wire contactor and the overload relay means. Actuation of a fusedprotector unit causes an ejector pin thereof to operate a common tripbar which, in turn, opens a switch in the coil circuit. This trip bar ispart of an anti-single phasing unit that is selectively positionablewith respect to the clips which mount the fused protector units, therebycooperating with fused protector units of different sizes. These clipsare provided with integral formations which serve a blocking ornon-interchangeability function, thereby preventing oversized fusedprotector units from being mounted to the clips. The antisingle phasingunit and protector unit holding clips are mounted on one disconnectswitch means mounted therein.

5 Claims, 14 Drawing Figures PATENIEU FEB 1 21974 SHEEI 1 0F 4 PATENTEBFEB] 2 I974 SHEEI 2 BF 4 ANTI-SINGLE PHASING DEVICE This inventionrelates to motor controls in general, and relates more particularly toan-improvement of the motor starter system disclosed in U. S. Pat. No.2,965,809 issued Dec. 20, 1960 to W. S. Edsall for Motor Starters.

Conventionally a motor is protected against electrical damage by anoverload relay. At currents slightly higher than locked rotor currentthe overload relay protects the motor branch circuit as long as themotor starter is self-protecting or the current is less than 13 timesfull load motor current, whichever is smaller. When bolted or arcingfaults cause higher currents to flow through the branch circuits, veryoften the branch wire, overload relay or contactor will be damaged ifthe branch circuit is not disconnected rapidly from the line.

The instant invention provides interrupting means in the form of fusedelements designated as motor short circuit protectors. These protectorsare constructed for circuit interruption in a short period of time atcurrents higher than indicated above, and are adapted to operate incoordination with conventional overload relays in order to protect theheaters of the latter at all currents higher than the current at whichthe overload relays protect themselves while utilizing the overloadrelays to effect interruption at running overloads or at lesser faultconditions.

The motor short circuit protectors, preferably one for each leg of thecircuit energizing the motor, are mounted to clips, resembling fuseclips, secured to one surface of a relatively shallow housing having amanually operable disconnect switch therein. Also mounted to the housingand selectively positionable thereon is an anti-single phasing deviceincluding a common tripper bar and a normally closed switch. Actuationof any of the motor short-circuit protectors is effective to release aspring biased pin thereof to operate the tripper bar which, in turn,operates the switch to open position to interrupt the holding circuitfor the electromagnetic contactors.

The clips include spaced arms having integrally formed projections thatact as a blocking or projection means which prevents utilization ofimproperly rated motor short circuit protectors.

Accordingly, a primary object of this invention is to provide a novelconstruction for an anti-single phasing device having particular use aspart of a motor control system.

Another object is to provide an anti-single phasing device that may bereadily and selectively located in a plurality of operative positionsfor operation in coordination with a range of differently rated motorshort circuit protectors.

These objects as well as other objects of this invention will becomereadily apparent after reading the following description of theaccompanying drawings in which:

FIG. 1 is an electrical schematic of a motor control system includingelements illustrated in detail in the other figures of thisspecification.

FIG. 2 is a plan view of the motor short circuit protector anddisconnect switch unit in combination with an anti-single phasing deviceconstructed in accordance with teachings of the instant invention.

FIG. 3 is a side elevation of the unit of FIG. 2 looking in thedirection of arrows 3-3 of FIG. 2.

FIG. 4 is an end view of the unit of FIG. 2 looking in the direction ofarrows 4-4 of FIG. 2.

FIG. 5 is an enlarged plan view, partially sectioned, of the anti-singlephasing unit.

FIG. 5A is a side elevation of the unit of FIG. 5 looking in thedirection of arrows 5A-5A of FIG. 5.

FIG. 6 is a front elevation of one of the clips for mounting a motorshort circuit protector unit.

FIGS. 6A, 6B and 6C are top, bottom and side elevations respectively ofthe clip of FIG. 6 looking in the direction of the respective pairs ofarrows 6A6A, 6B-6B, and 6C-6C of FIG. 6.

FIG. 7 is a side elevation of a blown motor short circuit protectorunit.

FIG. 7A is an end view of the unit of FIG. 7 looking in the direction ofarrows 7A-7A of FIG. 7.

FIG. 8 is a dimension chart correlating the structures of FIGS. 6C, 7and 7A.

FIG. 9 is a graph of MSCP and overload relay tripping characteristics.

Now referring to the Figures and more particularly to FIG. 1. Threephase motor 11 includes wye connected motor windings 12, 13, 14connected through lines r, s, t and individual heaters 18 to individualload terminals 15 of electromagnetic contact 16 having three movablecontacts 23. Heaters 18 are part of three phase overload relay l9 ofatype described in U. S. Pat. No. 3,288,964 issued Nov. 29, 1966 to J. B.Cataldo et al for a Spring Trip Multi-Phase Overload Relay Having aU-Shaped Bimetal with a Pivot Pin at Its Web Portion. In a manner wellknown to the art, when any of the heaters 18 becomes sufficientlyheated, bimetal means (not shown) is effective to open normally closedcontact means 21 and in so doing opens the energizing circuit for coil22 which operates main bridging contacts 23 into engagement with theirrespective load and line contacts 15 and 17.

Contacts 17 are connected through other sections of conductors r, s, tto load terminals 26 of the respective motor short circuit protectorunits (hereinafter MSCP) 25A, 25B, 25C whose respective line terminals27 are connected through an individual pole of three-phase disconnectswitch 28 to the respective energizing line R, S, and T. Each MSCP is ofa construction illustrated in the copending applications (CS-253) Ser.No. 98,423 now US. Pat. No. 3,663,915, filed Dec. 15, I970 and assignedto the assignee of the instant invention. In particular, each MSCP 25A,25B, 25C includes a fusable element (not shown) having a rupturingcharacteristic indicated by curve A in FIG. 9, which upon rupturingreleases striker pin 31 for engagement with common trip bar 32 ofantisingle phasing unit 33.

Unit 33 also includes bridging contact 34, biased by spring 35 towardengagement with stationary contacts 36, 37 that are connected throughlines 38, 39, respectively, to stop switch 41 and line r respectively.Thus, switch 34, 36, 37 is in the energizing circuit for contactoroperating coil 22, such circuit also including normally closed stopswitch 41 and holding contact 42, the latter being operated to closedposition by energization of coil 22. Normally open start switch 43parallels holding switch 42.

Disconnect switch 28 is generally of the type described in U. S. Pat.No. 3,349,208 issued Oct. 24, 1967 to J. B. Cataldo et al fora ToggleLever Actuated Manually Operated Circuit Controller, and includes moldedmain housing part 47 which encloses the disconnect switch contacts andoperating mechanism 199 controlled by handle 200. Upper surface 48 ofhousing 47 supports three pairs of spaced clips 51, 52 for mounting therespective MSCP's 25A, 25B, 25C. In particular, the clip 52 for MSCP 25Ais mounted by screw 53 to the raised leg of strap 54 whose lower leg isconnected by screw 55 to the load terminal of disconnect switch 28.

The other clip 51 for MSCP 25a is mounted to the upper surface of strap61 at one end of the latter with load terminal wire grip 62 being at theother end of strap 61. Screw 63 secures strap 61 to upper surface 48 ofswitch housing 47. Screws 68, 69 extending through a selected section ofthree section apertures 72, 73, respectively, in molded insulating base70 of anti-single phasing unit 33, secure unit 33 to housing surface 48in an operative position such that MSCP striker pins 31, when ejected,engage radially upward extending ears 74 of trip bar 32 to pivot thelatter in a counterclockwise direction with respect to FIG. A. Roll pins75, extending through elongated aperture 76 in cars 77 of trip bar 32 aswell as through cavity 78 in base 70, provide a pivotal mounting fortrip bar 32.

Switch contacts 34, 36, 37 are mounted within base cavity 79 havinginsulating cover sheet 81 mounted by four screws 82 to base 70. Operator83 is provided with a cut-out portion through which bridging contact 34extends and within which another contact pressure spring 84 is mounted.The force of spring 35 acting on plunger 83 is transmitted throughspring 84 to bias contact 34 toward closed position. Spring 35 biasesnose 83a of plunger 83 outside of cavity 79 into engagement with tripbar 32 in the midregion thereof, thereby urging trip bar 32 in aclockwise direction with respect to FIG. 5A.

MSCP 25A (FIGS. 7 and 7A) is provided with cylindrical body 25 havingaxially extending cylindrical terminals 26, 27 at opposite ends thereof.Striker pin 31 is also axially located, and prior to tripping of MSCP 25pin 31 is retained within terminal 26.

Since terminal clips 51, 52 have identical construction only one ofthese clips, clip 52, will be described in detail. With particularreference to FIGS. 6-6C, clip 52 is constructed of resilient conductingmaterial and is of generally U-shape having web 91 interconnecting armsor jaws 92, 93 which engage MSCP terminal 27 therebetween. Outwardlyextending ears 94 of web 91 are received by recesses in strap 54 toprevent rotation of clip 52. The edges of jaws 92, 93 remote from clip51 are each provided with integrally formed inward projection 95 whichis operatively positioned to block proper mounting of an MSCP unit thatis of excessive rating. Formed wire spring 97 urges jaws 92, 93 towardone another into firm electrical and mechanical engagement with MSCPterminal 27. As seen by studying the chart of FIG. 8 in relation toFIGS. 6C, 7 and 7A, MSCP 25 is one size unit in a family of three MSCPshaving different dimensions and different ratings, andnon-interchangeability formations 95 of clip 52 are operativelypositioned to block mounting of those members of this MSCP family thatare of excessive rating.

Reference is made to FIG. 9 which shows a steep current versus meltingtime characteristic of the MSCP in log-log scale. In particular, thecrossover point P between the MSCPs melting characteristic A and theoverload relay tripping characteristic B is chosen so that the MSCP willoperate to cause opening of the operator coil circuit under severeoverload conditions. In order to protect overload relay heaters 18 andmotor 11, and to prevent nuisance blowing of the MSCP, crossover point Pis generally in the range from 5.5 to 13 times full load current ofmotor 11 depending upon the current up to which overload relay 19 isselfprotecting. For running overload conditions and currents undercrossover point P of the two characteristics A and B, opening of thecircuit for energizing coil 22 is caused by the operation of overloadrelay means 19.

Thus, it is seen that the instant invention provides a novel motorcontrolling system which includes a novel construction for ananti-single phasing unit utilizing a common tripper bar acted upon bystriker pins of blown motor short circuit protectors.

Although there has been described a preferred embodiment of this novelinvention, many variations and modifications will now be apparent tothose skilled in the art. Therefore, this invention is to be limited notby the specific disclosure herein but only by the appending claims.

I claim:

1. An anti-single phasing device including'a molded base having acavity, switch contact means operable between an open and a closedposition within said cavity, a switch operator projecting from saidcavity, biasing means within said cavity urging said switch contactmeans to one of its said positions and urging said switch contact meansto one of its said positions and urging said operator to project fromsaid cavity, an elongated trip bar, mounting means securing said bar tosaid base for movement toward and away from said cavity about a pivotalaxis generally parallel to the longitudinal axis of said bar, saidoperator engaging said bar at a point intermediate the ends thereof,whereby movement of said bar toward said cavity forces said operatorinto said cavity to operate said switch contact means to the other ofits said positions and a plurality of elongated multisection mountingformations for selectively and predeterminedly positioning said devicewith respect to means for operating said bar.

2. A device as set forth in claim 1 in which the bar includes first andsecond radial ears positioned on opposite sides of the point ofengagement between said operator and said bar, said base includingrecesses into which said ears extend, said mounting means including pinsextending into said recesses and said ears.

3. A device as set forth in claim 2 in which the pins are generallyperpendicular to the pivotal axis.

4. A device as set forth in claim 3 in which each of the elongatedmultisection mounting formations is an aperture defined by first andsecond elongated sidewalls each including a plurality of adjacentconcave sections operatively positioned with the concave sections ofsaid first sidewall aligned with and facing the concave sections of saidsecond sidewall.

5. A device as set forth in claim 1 in which each of the elongatedmultisection mounting formations is an aperture defined by first andsecond elongated sidewalls each including a plurality of adjacentconcave sections operatively positioned with the concave sections ofsaid first sidewall aligned with and facing the concave sections of saidsecond sidewall.

1. An anti-single phasing device including a molded base having acavity, switch contact means operable between an open and a closedposition within said cavity, a switch operator projecting from saidcavity, biasing means within said cavity urging said switch contactmeans to one of its said positions and urging said switch contact meansto one of its said positions and urging said operator to project fromsaid cavity, an elongated trip bar, mounting means securing said bar tosaid base for movement toward and away from said cavity about a pivotalaxis generally parallel to the longitudinal axis of said bar, saidoperator engaging said bar at a point intermediate the ends thereof,whereby movement of said bar toward said cavity forces said operatorinto said cavity to operate said switch contact means to the other ofits said positions and a plurality of elongated multisection mountingformations for selectively and predeterminedly positioning said devicewith respect to means for operating said bar.
 2. A device as set forthin claim 1 in which the bar includes first and second radial earspositioned on opposite sides of the point of engagement between saidoperator and said bar, said base including recesses into which said earsextend, said mounting means including pins extending into said recessesand said ears.
 3. A device as set forth in claim 2 in which the pins aregenerally perpendicular to the pivotal axis.
 4. A device as set forth inclaim 3 in which each of the elongated multisection mounting formationsis an aperture defined by first and second elongated sidewalls eachincluding a plurality of adjacent concave sections operativelypositioned with the concave sections of said first sidewall aligned withand facing the concave sections of said second sidewall.
 5. A device asset forth in claim 1 in which each of the elongated multisectionmounting formations is an aperture defined by first and second elongatedsidewalls each including a plurality of adjacent concave sectionsoperatively positioned with the concave sections of said first sidewallaligned with and facing the concave sections of said second sidewall.